It's known as the Konami code. It appeared for the first time in the excellent game Contra, where you can have kind of everything with it. And nowadays it's still present, hidden, everywhere, on video games, website etc. Not in deviantart.com, though. Not yet ...

Hmmm... being french, I don't get the first word. I mean, I understand the message so I can extrapolate that it's "I", but why what is a coin to me is equals to "I" ? Thanks for your help for foreigners